Self-venting balloon dilatation catheter and method

ABSTRACT

Self-venting balloon dilatation catheter having a flexible tubular member with first and second lumens extending therethrough. An inflatable balloon is carried by the distal extremity of the tubular member in such a manner so that the first lumen extends through the balloon and is out of communication with the interior of the balloon and the second lumen is in communication with the interior of the balloon. A venting device is disposed between the balloon and the tubular member for venting air from the interior of the balloon but inhibiting the escape of liquid from the balloon.

.Iadd.This is a continuation of the application Ser. No. 07/303,384which was filed on Jan. 27, 1989, now abandoned. .Iaddend.

This invention relates to balloon dilatation catheters and moreparticularly to such catheters having a self-venting balloon and amethod for making the same.

In utilizing balloon dilatation catheters, it is necessary that theballoon be filled with a liquid. In the filling of the balloon, it isdesirable that the air which is within the balloon be expelled from theballoon but the air is compressible. In the past this has beenaccomplished by successively aspirating the balloon with fluid. The airis withdrawn during the repeated evacuation. This has a disadvantage inthat it can be difficult to ensure complete removal of all the air.Alternatively, the air removal is accomplished by providing a separatetube which may be removable which extends from the proximal extremity ofthe catheter into the balloon so that during the time that the liquid isbeing introduced into the balloon, the air in the balloon can beexpelled through the separate tube. The use of such a separate tube hasa disadvantage, particularly when it is desired to provide a dilatationcatheter which has a very low profile in that it makes it more difficultto reduce the profile of the dilatation catheter. There is therefore aneed for a new and improved balloon dilatation catheter which overcomesthese limitations.

In general it is an object of the present invention to provide a balloondilatation catheter which is self-venting.

Another object of the invention is to provide a dilatation catheter ofthe above character in which the air is vented through the distalextremity of the catheter.

Another object of the invention is to provide a balloon dilatationcatheter of the above character in which the air in the balloon isvented while the leakage of any liquid from the balloon is inhibited.

Another object of the invention is to provide a balloon dilatationcatheter of the above character which ensures complete removal of theair without aspiration.

Another object of the invention is to provide a method for constructingthe catheter of the present invention.

Additional objects and features of the invention will appear from thefollowing description in which the preferred embodiment is set forth indetail in conjunction with the accompanying drawing.

FIG. 1 is a side elevational view of a balloon dilatation catheterincorporating the present invention.

FIG. 2 is a cross sectional view of the distal extremity of the balloondilatation catheter shown in FIG. 1.

FIG. 3 is a cross sectional view taken along the line 3--3 of FIG. 2.

FIG. 4 is a cross sectional view showing the method which is utilized inmanufacturing the balloon dilatation catheter shown in FIGS. 1-3.

In general, the self-venting balloon dilatation catheter of the presentinvention is comprised of a flexible tubular member having first andsecond lumens extending therethrough. An inflatable balloon is carriedby the distal extremity of the tubular member in such a manner so thatthe first lumen extends through the balloon and is out of communicationwith the interior of the balloon and the second lumen is incommunication with the interior of the balloon. A vent system isdisposed between the balloon and the tubular member for venting air fromthe interior of the balloon but inhibiting the escape of liquid from theballoon.

More in particular as shown in FIGS. 1-3 of the drawing, the balloondilatation catheter 10 incorporated the present invention is comprisedof a tubular member 11 which consists of a first tubular element 12which has a lumen 13 extending therethrough. It also consists of asecond tubular element 14 which is coaxially disposed on the firsttubular element 12 and provides in conjunction with the first tubularelement an annular lumen which extends longitudinally of the first andsecond tubular elements 12 and 14. An expandable balloon 17 is carriedby the second tubular element 14 of the member 11 near the distalportion thereof and has its interior in communication with the lumen 16.The balloon 17 extends concentrically about the first tubular element12. Although the balloon 17 can be formed as a separate element whichhas its extremities bonded to the second tubular element 14, it ispreferably formed integral with the second tubular element as shown. Thetubular elements 12 and 14 are formed of a suitable flexiblethermo-plastic material such as a polyolefin or polyvinychloride.

The distal extremities of the first and second tubular elements 12 and14 are bonded together in a suitable manner so as to form a liquid-tightseal between the same. Typically this can be accomplished by applyingheat to the distal extremity of the second tubular element with amandrel disposed in the distal extremity of the first tubular elementand applying heat to shrink the distal extremity of the second tubularelement onto the first tubular element to form such a seal.

Means is provided in the distal extremity of the first and secondtubular elements for venting air from the balloon 17 while inhibitingthe escape of liquid from the balloon 17 and consists of a very smallpassage 21 which is disposed between the distal extremities of the firstand second tubular elements 12 and 14 and which extends from theinterior of the balloon 17 to ambient at the distal extremity of thecatheter 11. The flow passage 21 can be formed in any suitable manner.One method found to be particularly efficacious is as follows inconjunction with FIG. 4. A piece 22 of suitable wire such as tungsten isused because of its good tensile strength. The wire 22 should have adiameter which is less than 0.001 inches as, for example, 0.0005 inches.It is coated with silicone. After the wire 22 has been coated withsilicone, it is inserted by a tweezes between the distal extremities ofthe first and second tubular elements 12 and 14 prior to the time thatthe second tubular element 14 is heat shrunk onto the first tubularelement as hereinbefore described. As soon as the tungsten wire 22 hasbeen inserted into the distal extremities of the first and secondtubular elements 12 and 14 so that it extends into the balloon 17 andout the distal extremities as shown in FIG. 4, a mandrel 23 is insertedinto the lumen 13. Heat is then applied to the distal extremity of thesecond tubular element 14 to cause it to form a shrink fit between itand the distal extremity of the first tubular element 12 and at the sametime to shrink down around the wire 22. After the distal extremity ofthe catheter has been cooled, the mandrel 23 can be removed and the wire22 can be pulled out with tweezers leaving the cylindrical flow passage21 hereinbefore described.

It should be appreciated that if desired, more than one hole or passage21 can be provided to make the balloon venting procedure more rapid. Italso should be appreciated that other means can be provided in thedistal extremity of the catheter in place of the passage 21 for makingthe balloon 17 self-venting. For example, braided fibers can be utilizedin the distal extremity of the catheter in the same manner as thetungsten wire 22 has been utilized. In such a case, the fibers can beleft in place so that the air can flow between interstices of thebraided fibers. Alternatively, hollow fiber or fibers can beincorporated into the distal extremity of the catheter. Alternatively,hydrophobic filter material can be incorporated between the distalextremities of the first and second tubular elements 12 and 14. Thisfilter material is capable of passing air but inhibits the passage ofliquid from the balloon 17.

The remainder of the balloon dilatation catheter shown in FIG. 1 issubstantially conventional. A side arm adapter 26 is provided which hasa main or central arm 27 and a side arm 28. A guide wire 29 extendsthrough the main or central arm 27 and extends through the lumen 13 ofthe first tubular element 12 and has a distal extremity extending beyondthe distal extremity of the dilatation catheter 11. A torquer 31 issecured to the proximal extremity of the guide wire 29 and is utilizedfor extending and retracting the guide wire and also for rotating theguide wire.

Use of the self-venting balloon dilatation catheter may now be brieflydescribed as follows. The balloon 17 is first inflated outside of thehuman body by introducing a radiographic contrast liquid through theside arm 28 so that it passes through the annular lumen 16 between thefirst and second tubular elements 12 and 14 and passes into the balloon17. The air which is in the balloon is pushed forwardly in the balloonand under the pressure of the radiographic contrast liquid is forced topass out through the small passage 21 provided between the distalextremities of the first and second tubular elements 12 and 14. Byutilizing a passage 21 having a diameter of 0.0005 inches, it has beenfound that a two millimeter diameter balloon having a length ofapproximately 25 millimeters can be completely rid of air in less thanapproximately 40 seconds. The size of the passage 21 is such that itinhibits the escape of the radiographic contrast liquid so that verylittle, if any, of the liquid can escape, even though pressure up to 200psi for the radiographic contrast liquid is attained within the balloon17. As soon as the balloon 17 has been inflated with the radiographiccontrast liquid and the air has been expelled therefrom through thepassage 21, the liquid can be withdrawn to deflate the balloon 17. Theballoon dilatation catheter is now ready to be inserted into the humanbody. After the balloon 17 has been positioned in the stenosis in thearterial vessel in the human body, the balloon can be again inflated byreintroducing radiographic contrast liquid through the side arm 28through the lumen 16 and into the balloon 17. Since all of the air haspreviously been expelled from the balloon 17, the balloon can be readilyinflated within the stenosis to its full diameter at the desiredpressure as, for example, in excess of 100 psi without danger of anysignificant amount of radiopaque contrast liquid passing through thepassage 21. After the opening in the stenosis has been enlarged, theballoon can be deflated and the dilatation catheter can be removed.

It is apparent from the foregoing that there has been provided a balloondilatation catheter which is self-venting and in which the balloon canbe inflated to the desired pressure without danger of any significantamount of radiopaque contrast liquid passing through the venting orificeprovided in the distal extremity of the balloon dilatation catheter. Theventing orifice formed in the distal extremity of the balloon dilatationcatheter is formed in such a manner sot that it can be readilyincorporated into the manufacturing process for making the balloondilatation catheters.

What is claimed is:
 1. In a self-venting balloon dilatation catheter, aflexible tubular member having first and second lumens extendingtherethrough, an inflatable balloon carried by the distal extremity ofthe tubular member in such a manner so that the first lumen extendsthrough the balloon and is out of communication with .[.that.]..Iadd.the .Iaddend.the interior of the balloon and the second lumen isin communication with the .[.distal extremity.]. interior of the balloonand .[.means disposed between the balloon and tubular member.]. .Iadd.apassageway having a transverse cross-sectional dimension less than about0.001 inch extending from the interior of the balloon to ambient.Iaddend.for venting air from the interior of the balloon but inhibitingthe escape of liquid from the balloon.
 2. A dilatation catheter as inclaim 1 wherein said means is disposed between the balloon and a tubularmember for venting air comprised of a flow passage having a diameter ofless than approximately 0.001 inch.
 3. A dilatation catheter as in claim2 wherein said means is disposed between the balloon and the tubularmember includes hydrophobic material.
 4. A dilatation catheter as inclaim 1 wherein said tubular member is comprised of a first tubularelement having the first lumen extending therethrough, a second tubularelement coaxially disposed over said first tubular element and formingthe second lumen extending between the first and second tubular membersand wherein the expandable balloon is carried by the second tubularelement and has its interior in communication with the second lumenbetween the first and second tubular elements.
 5. In a self-ventingballoon dilatation catheter, a first tubular element having a lumenextending therethrough, a second tubular element coaxially disposed oversaid first tubular element and forming a lumen extending between thefirst and second tubular members, an expandable balloon carried by thesecond tubular element and having its interior in communication with thelumen between the first and second tubular elements and means disposedbetween the distal extremities of the first and second tubular elementsfor venting air from the interior of the balloon but inhibiting escapeof a liquid from the balloon.
 6. A dilatation catheter as in claim 5wherein said means disposed between the distal extremities of the firstand second tubular elements for venting air comprises a flow passagehaving a diameter less than approximately 0.001 inches.
 7. A dilatationcatheter as in claim 6 wherein said means disposed between the distalextremities of the first and second tubular elements includeshydrophobic material.
 8. A balloon dilatation catheter as in claim 5wherein said means disposed between the distal extremities of the firstand second tubular elements for venting air includes members disposedbetween the first and second tubular elements permitting the escape ofair from the interior of the balloon but inhibiting the escape ofliquids from the balloon.
 9. A dilatation catheter as in claim 5 whereinsaid first and second tubular elements are formed of thermoplasticmaterials.
 10. A dilatation catheter as in claim 9 wherein the distalextremities of the first and second tubular elements are sealed by aheat shrink seal. .Iadd.
 11. A self-venting vascular comprising:a) aflexible tubular member having at least one inner lumen extendingtherethrough to an interior portion of the catheter with means toreceive liquid under pressure; b) a venting means with a flowrestrictive passageway having a transverse cross-sectional dimensionless than about 0.001 inch extending from the interior portion of thecatheter to ambient which allows air but no substantial amount of liquidto pass therethrough while a pressure in excess of 100 psi is maintainedin the interior of the catheter. .Iaddend. .Iadd.12. The self-ventingcatheter of claim 11 wherein the flow restrictive passageway of theventing means has circular transverse cross-sectional shape with adiameter of less than about 0.001 inch. .Iaddend. .Iadd.13. Theself-venting catheter of claim 11 wherein the flow restrictivepassageway of the venting means includes braided fibers. .Iaddend..Iadd.14. The self-venting catheter of claim 11 wherein the flowrestrictive passageway of the venting means includes hydrophobic filtermaterial. .Iaddend. .Iadd.15. The self-venting catheter of claim 11wherein the flow restrictive passageway of the venting means will allowno substantial amounts of inflating liquid to pass therethrough atpressures in excess of 100 psi. .Iaddend. .Iadd.16. In a balloondilatation catheter comprising an elongated tubular member with aninflatable balloon on the distal portion thereof and with an inner lumenextending therein which is in fluid communication with the interior ofthe balloon and which directs inflating liquid therein, the improvementcomprising an air venting means which includes at least one flowrestrictive passageway having a transverse cross-sectional dimensionless than about 0.001 inch extending between the balloon interior andambient which allows air but no substantial amounts of inflating liquidto pass therethrough while a pressure in excess of 100 psi is maintainedin the balloon interior. .Iaddend. .Iadd.17. The balloon dilatationcatheter of claim 16 wherein the flow restrictive passageway has acircular transverse shape with a diameter less than about 0.001 inch..Iaddend. .Iadd.18. The balloon dilatation catheter of claim 16 whereinthe flow restrictive passageway contains braided fibers. .Iaddend..Iadd.19. The balloon dilatation catheter of claim 16 wherein the flowrestrictive passageway contains hydrophobic filter material. .Iaddend..Iadd.20. The balloon dilatation catheter of claim 16 wherein aplurality of flow restrictive passageways are provided. .Iaddend..Iadd.21. The balloon dilatation catheter of claim 16 wherein the flowrestrictive passageway will allow no substantial amounts of inflatingliquid to pass therethrough at liquid pressures in excess of 100 psi..Iaddend. .Iadd.22. The balloon dilatation catheter of claim 16 whereinthe flow restrictive passageway extends in a distal direction from theinterior of the balloon. .Iaddend. .Iadd.23. The balloon dilatationcatheter of claim 16 wherein the balloon has a distal end which issealingly bonded to an inner member. .Iaddend. .Iadd.24. The balloondilatation catheter of claim 23 wherein the flow restrictive passagewayof the venting means extends from the interior of the balloon to ambientin a distal direction between the distal end of the balloon and theinner member. .Iaddend.